1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/bitops.h>
3 #include <linux/kernel.h>
4 #include <linux/random.h>
5 #include <linux/slab.h>
6 #include <linux/types.h>
7
8 #include "drm_random.h"
9
drm_prandom_u32_max_state(u32 ep_ro,struct rnd_state * state)10 static inline u32 drm_prandom_u32_max_state(u32 ep_ro, struct rnd_state *state)
11 {
12 return upper_32_bits((u64)prandom_u32_state(state) * ep_ro);
13 }
14
drm_random_reorder(unsigned int * order,unsigned int count,struct rnd_state * state)15 void drm_random_reorder(unsigned int *order, unsigned int count,
16 struct rnd_state *state)
17 {
18 unsigned int i, j;
19
20 for (i = 0; i < count; ++i) {
21 BUILD_BUG_ON(sizeof(unsigned int) > sizeof(u32));
22 j = drm_prandom_u32_max_state(count, state);
23 swap(order[i], order[j]);
24 }
25 }
26 EXPORT_SYMBOL(drm_random_reorder);
27
drm_random_order(unsigned int count,struct rnd_state * state)28 unsigned int *drm_random_order(unsigned int count, struct rnd_state *state)
29 {
30 unsigned int *order, i;
31
32 order = kmalloc_array(count, sizeof(*order), GFP_KERNEL);
33 if (!order)
34 return order;
35
36 for (i = 0; i < count; i++)
37 order[i] = i;
38
39 drm_random_reorder(order, count, state);
40 return order;
41 }
42 EXPORT_SYMBOL(drm_random_order);
43